Hydantoins thiohydantoins

Lempert, K., J. Nyitrai, P. Sohar and K. Zauer Hydantoins, thiohydantoins and glycocyamidines. Tetrahedron Letters 2679, (1964). 

See Tables of Compounds in Ellis and Honeyman for data on glycosyl isocyanates and isothiocyanates, and glycosyl-urethans, -thiourethans, -hydantoins, -thiohydantoins, and related compounds. 

Hydantoins, thiohydantoins, and their substituted products are particularly useful as catalysts and as stabilizer agents in polymer chemistry and also in the preparation of epoxy resins.356,357 Thus hydantoins 148 are readily hardened, giving suitable polymers for the preparation of molding and lacquers. 

Substances showing catalytic waves in ammoniacal cobalt or nickel solutions< > must fulfil another condition beside the two conditions mentioned above the substance has to form a complex-compound with cobalt and other components of the solution. Moreover, the acid properties of this complex and its adsorbability also seem to be of importance. The substances showing a catalytic effect of this type usually contain at least an atom of sulphur in their molecule (e.g. cysteine, dithiopyrimidine or proteins). Whether or not the presence of sulphur in the catalytically active molecule is a sufficient condition has yet to be decided. It was shown that e.g. gelatin or casein containing little or no sulphur atoms do not produce any catalytic wave of this type. Similarly, in the series of hydantoin, thiohydantoin and dithiohydantoin as well as pyrimidine, thiopyrimidine, and dithiopyrimidine, the catalytic effect was only observed for the thioderivative and it increased with the number of sulphur atoms in the molecule. 

In 1873, almost simultaneously, Maly (24), Volhard (38), and Nencki (42) studied the action of thiourea on chloroacetic acid. As mentioned previously, they believed the product to be the thioanalog of hydantoin and called it thiohydantoin with formula 34. 

Thiohydantoin [503-87-7] (pi C 8.5) is a slightly stronger acid than hydantoin (pi C 9.0). 4-Thiohydantoins appear to be weaker acids (4). 

Hydantoin derivatives show weak absorption in the uv-visible region, unless a part of the molecule other than the imidazohdinedione ring behaves as a chromophore (13) however, piC values have been determined by spectrophotometry in favorable cases (14). Absorption of uvby thiohydantoins is more intense, and the two bands observed have been attributed to n — tt and n — tr transitions of the thiocarbonyl group (15,16). Several piC values of thiohydantoins have been determined by uv-visible spectrophotometry (16). 

Mass spectral fragmentation patterns of alkyl and phenyl hydantoins have been investigated by means of labeling techniques (28—30), and similar studies have also been carried out for thiohydantoins (31,32). In all cases, breakdown of the hydantoin ring occurs by a-ftssion at C-4 with concomitant loss of carbon monoxide and an isocyanate molecule. In the case of aryl derivatives, the ease of formation of Ar—NCO is related to the electronic properties of the aryl ring substituents (33). Mass spectrometry has been used for identification of the phenylthiohydantoin derivatives formed from amino acids during peptide sequence determination by the Edman method (34). 

Reactions at G-5. The C-5 atom of hydantoins can be considered as an active methylene group, and therefore is a suitable position for base-cataly2ed condensation reactions with aldehydes (44). 2-Thiohydantoins give the reaction more readily than their oxygen counterparts ... 

A comparative study was carried out of the effectiveness of three commercially available chiral columns and nonchiral derivatives of amino acids such as A-(3,5-dinitrobenzoyl) esters (119), phenylurea esters (120), hydantoins (121) and thiohydantoins (98). Although good separations were obtained, no column was universally effective294. 

Condensation of formyl-pyrroles and -indoles with a wide range of other activated methylene compounds has been reported. These include, for example, hydantoin, which provides a useful synthetic route to tryptophane and j8- (pyrrolyl)alanines, thiohydantoin, rhodanine and AT-substituted barbituric acids (B-77MI30505, 79HC(25-3)357). Flash pyrolysis of the condensation product derived from 3-formyl-2,5-dimethylpyrrole with Meldrum s acid produces 6-hydroxy-2-methylindole, (440) — (441) (74AJC2605), whilst the analogous... 

Figure 15.8. Strategies for the preparation of hydantoins and thiohydantoins on insoluble supports. X O, S.

Fig. 3. Solid-phase synthesis of hydantoin and thiohydantoin libraries from resin-bound dipeptides.

To increase the number of diversities, the hydantoin (or thiohydantoin) formation reaction was performed starting from N-alkylated dipeptides (Fig. 3). In the last synthesis step, the hydantoin (or thiohydantoin) ring was alkylated followed by the cleavage from the resin. Using 54 different amino acids for the first position of diversity (R1), 60 different amino acids for the second position of diversity (R2), and four different alkylating... 

An efficient solid-phase protocol for the synthesis of substituted (5-biphenyltetrazolyl)-hydantoins and -thiohydantoins has been developed. Suzuki cross-coupling between resin-bound 2-(tetrazol-5-yl)-phenylborinane 333 and 4-bromobenzaldehyde gave the corresponding tetrazolylbiphenyl aldehyde 334 (Equation 59) <2004BML317>. 

Nefzi, A., Giulianotti, M Truong, L., Rattan, S Ostresh, J. M and Houghten, R. A., (2002) Solid-phase synthesis of linear ureas tethered to hydantoins and thiohydantoins. / Comb. Chem. 4, 175-178. 

Among radicals from diazoles, in the imidazole series hydantoin, methyl-hydantoin, and thiohydantoin have given various radicals e.g., 159, differing in degree of protonation, upon radiolysis of aqueous solutions.546 Values of... 

Spiro hydantoins, (III) prepared by Webb (4) and hydantoin and thiohydantoin, (IV), derivatives prepared by Poitout (5) were effective as somatostatin receptor agonists and were useful in treating hypersecretion disorders. 

A fluorous catch and release method was used by Zhang in the synthesis of di-substituted pyrimidines.A fluorous route to hydantoins and thiohydantoins was also reported by the same group. 

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